1. Field of the Invention
This invention relates to a process for hydrocracking of heavy oil feeds using a dispersed dual function catalyst which is prepared in situ.
2. Description of the Prior Art
Hydrorefining processes utilizing dispersed calalysts in admixture with a hydrocarbonaceous oil are well known. The term "hydrorefining" is intended herein to designate a catalytic treatment, in the presence of hydrogen, of a hydrocarbonaceous oil to upgrade the oil by eliminating or reducing the concentration of contaminants in the oil such as sulfur compounds, nitrogenous compounds, metal contaminants and/or to convert at least a portion of the heavy constituents of the oil such as asphaltenes or coke precursors to lower boiling hydrocarbon products, and to reduce the Conradson carbon residue of the oil.
U.S. Pat. No. 3,161,585 discloses a hydrorefining process in which a petroleum oil chargestock containing a colloidally dispersed catalyst selected from the group consisting of a metal of Groups VB and VIB, an oxide of said metal and a sulfide of said metal is reacted with hydrogen at hydrorefining conditions. This patent teaches that a concentration of the dispersed catalyst, calculated as the elemental metal, in the oil chargestock is from about 0.1 weight percent to about 10 weight percent of the initial chargestock.
U.S. Pat. No. 3,331,769 discloses a hydrorefining process in which a metal component (Group VB, Group VIB, iron group metal) colloidally dispersed in a hydrocarbonaceous oil is reacted in contact with a fixed bed of a conventional supported hydrodesulfurization calalyst in the hydrorefining zone. The concentration of the dispersed metal component which is used in the hydrorefining stage in combination with the supported catalyst ranges from 250 to 2500 weight parts per million (wppm).
U.S. Pat. No. 3,657,111 discloses a process for hydrorefining an asphaltene-containing hydrocarbon chargestock which comprises dissolving in the chargestock a hydrocarbon-soluble oxovanadata salt and forming a colloidally dispersed catalytic vanadium sulfide in situ within the chargestock by reacting the resulting solution, at hydrorefining conditions, with hydrogen and hydrogen sulfide.
U.S. Pat. No. 3,131,142 discloses a slurry hydrocracking process in which an oil soluble dispersible compound of Groups IV to VIII is added to a heavy oil feed. The catalyst is used in amounts ranging from 0.1 to 1 weight percent, calculated as the metal, based on the oil feed.
U.S. Pat. No. 1,876,270 discloses the use of oil soluble organometallic compounds in thermal cracking or in destructive hydrogenation (hydrocracking) of hydrocarbons to lower boiling products.
U.S. Pat. No. 2,091,831 discloses cracking or destructive hydrogenation carried out in the presence of oil soluble salts of acid organic compounds selected from the group consisting of carboxylic acids and phenols with a metal of Group VI and Group VIII of the Periodic Table. The oil soluble salt is used in amounts between 4 and 20 weight percent based on the feed.
A closely related approach is disclosed in U.S. Pat. No. 4,226,742, the entire contents of which are incorporated herein by reference. This patent discloses dissolving an oil soluble metal compound in oil, and converting the compound to a solid, non-colloidal catalyst within the oil and reacting the oil containing the catalyst with hydrogen. Addition of about 10 to about 950 weight ppm of metal or metals as oil soluble compounds is preferred.
U.S. Pat. No. 3,235,508, the entire contents of which are incorporated herein by reference, discloses the advantages obtained by using a colloidal dispersion of catalyst for conversion of heavy crude oils. Examples were given of use of 0.2 to 3.6 weight percent of an impregnated catalyst dispersed in a topped crude. A crude and catalyst mixture, containing 3.6 weight percent catalyst was tested. This catalyst contained 2.0 weight percent cobalt oxide and 4.3 weight percent molybdenum oxide, equivalent to 15 to 20,000 weight part per million cobalt metal and molybdenum metal present in the feed.
In U.S. Pat. No. 4,313,818, the entire contents of which are incorporated herein by reference, a catalyst is made in situ in the reactor by charging oil and a catalyst precursor along with hydrogen, and optionally but preferably with H.sub.2 S to a reactor. The oil should have a high Conradson carbon content. In the reducing atmosphere of the reaction zone, the soluble catalyst precursor compounds are reduced and coprecipitated with asphaltic material to produce a high surface area catalyst.
A hydrovisbreaking approach with dispersed catalyst is disclosed in U.S. Pat. No. 4,411,770, the entire contents of which is incorporated herein by reference. The acidic component (ZSM-5 or zeolite beta) and metal component are mixed together and extruded or the metal is added by impregnation. The process upgraded residual fractions, with a limited amount of conversion of the resid to lighter products.
We reviewed the work that others had done with a view towards finding an improved process which would permit the economical upgrading of heavy crude oil fractions or other heavy synthetic fuels.
We learned that it was possible to efficiently and economically upgrade these heavy streams by adding to the stream a metal component, as a thermally decomposable compound, while separately adding an acidic solid catalyst.